(1) Field of the Invention
The present invention relates to compositions and formulations comprising insulin or insulin analogues comprising a carboxy terminal portion (CTP) peptide comprising amino acids 112-118 to 145 of the beta subunit of human chorionic gonadotropin (hCGβ) or a partial variant thereof that includes at least one O-glycosylation site of the CTP peptide, wherein the CTP peptide of the CTP peptide-based insulin or insulin analogue is O-glycosylated. In particular embodiments, the O-glycosylated insulin analogues are produced in vivo and in further embodiments, the O-glycosylated CTP-based insulin analogues comprise predominantly mannotriose and mannotetrose O-glycans or predominantly mannose O-glycans.
(2) Description of Related Art
Insulin is a peptide hormone that is essential for maintaining proper glucose levels in most higher eukaryotes, including humans. Diabetes is a disease in which the individual cannot make insulin or develops insulin resistance. Type I diabetes is a form of diabetes mellitus that results from autoimmune destruction of insulin-producing beta cells of the pancreas. Type II diabetes is a metabolic disorder that is characterized by high blood glucose in the context of insulin resistance and relative insulin deficiency. Left untreated, an individual with Type I or Type II diabetes will die. While not a cure, insulin is effective for lowering glucose in virtually all forms of diabetes. Unfortunately, its pharmacology is not glucose sensitive and as such it is capable of excessive action that can lead to life-threatening hypoglycemia. Inconsistent pharmacology is a hallmark of insulin therapy such that it is extremely difficult to normalize blood glucose without occurrence of hypoglycemia. Furthermore, native insulin is of short duration of action and requires modification to render it suitable for use in control of basal glucose. One central goal in insulin therapy is designing an insulin formulation capable of providing a once a day time action. Mechanisms for extending the action time of an insulin dosage include decreasing the solubility of insulin at the site of injection or covalently attaching sugars, polyethylene glycols, hydrophobic ligands, peptides, or proteins to the insulin.
Molecular approaches to reducing solubility of the insulin have included (1) formulating the insulin as an insoluble suspension with zinc and/or protamine, (2) increasing its isoelectric point through amino acid substitutions and/or additions, such as cationic amino acids to render the molecule insoluble at physiological pH, or (3) covalently modifying the insulin to include a hydrophobic ligand that reduces solubility of the insulin and which binds serum albumin. All of these approaches have been limited by the inherent variability that occurs with precipitation of the molecule at the site of injection, and with the subsequent re-solubilization and transport of the molecule to blood in the form of an active hormone. Even though the resolubilization of the insulin provides a longer duration of action, the insulin is still not responsive to serum glucose levels and the risk of hypoglycemia remains.
Insulin is a two chain heterodimer that is biosynthetically derived from a low potency single chain proinsulin precursor through enzymatic processing. The human insulin analogue consists of two peptide chains, an “A-chain peptide” (SEQ ID NO: 33) and “B-chain peptide” (SEQ ID NO: 25)) bound together by disulfide bonds and having a total of 51 amino acids. The C-terminal region of the B-chain and the two terminal ends of the A-chain associate in a three-dimensional structure that assembles a site for high affinity binding to the insulin receptor. The insulin molecule does not contain N-glycosylation.
Insulin molecules have been modified by linking various moieties to the molecule in an effort to modify the pharmacokinetic or pharmacodynamic properties of the molecule. For example, acylated insulin analogs have been disclosed in a number of publications, which include for example U.S. Pat. Nos. 5,693,609 and 6,011,007. PEGylated insulin analogs have been disclosed in a number of publications including, for example, U.S. Pat. Nos. 5,681,811, 6,309,633; 6,323,311; 6,890,518; 6,890,518; and, 7,585,837. Glycoconjugated insulin analogs have been disclosed in a number of publications including, for example, Internal Publication Nos. WO06082184, WO09089396, WO9010645, U.S. Pat. Nos. 3,847,890; 4,348,387; 7,531,191; and, 7,687,608. Remodeling of peptides, including insulin to include glycan structures for PEGylation and the like have been disclosed in publications including, for example, U.S. Pat. No. 7,138,371 and U.S. Published Application No. 20090053167.